Method for Detecting Sent Sequence, Receiver, and Receiving Device

ABSTRACT

A method for detecting a sent sequence, a receiver, and a receiving device in order to simplify an algorithm for detecting a sent sequence and improve detection efficiency. The method for detecting a sent sequence includes determining a maximum possible candidate value of each element in N elements of a received element sequence to obtain N maximum possible candidate values, where N is a positive integer, determining state sequences corresponding to the N maximum possible candidate values as reserved sequences to obtain N groups of reserved sequences, performing likelihood computation on the N groups of reserved sequences, and setting a reserved sequence that is in the N groups of reserved sequences and is most consistent with the element sequence as a detected sent sequence.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of International Patent ApplicationNo. PCT/CN2014/093381 filed on Dec. 9, 2014, the disclosure of which ishereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to the communications field, and inparticular, to a method for detecting a sent sequence, a receiver, and areceiving device.

BACKGROUND

In a communications system, a receiver is used to receive a signal, anddetermine, through computation, a sent sequence that is on a sendingterminal and corresponds to a received sequence. In algorithms fordetermining a sent sequence, maximum likelihood sequence estimation(MLSE) can compensate for linear and nonlinear losses in the system,reduce a bit error rate, and achieve a better effect.

A basic principle of MLSE is to find, among all possible sent sequences,a sequence that is most consistent with a received sequence, and setthis possible sent sequence as a detected sent sequence. Generally, aViterbi algorithm (VA) is used to make complexity no longer related to aquantity of elements in a sequence, and thereby reduce complexity ofMLSE. In this case, the two algorithms are jointly referred to asMLSE-VA. A consideration of the VA is to remove a survivor path thatcannot become a maximum likelihood selection object on a latticediagram.

However, in high-order quadrature amplitude modulation (QAM), as asystem order increases, a quantity of operations in the MLSE-VAalgorithm increases exponentially. Therefore, a method for detecting asent sequence still includes a large quantity of operations and has lowefficiency.

SUMMARY

The present disclosure provides a method for detecting a sent sequence,a receiver, and a receiving device in order to simplify an algorithm fordetecting a sent sequence and improve detection efficiency.

According to a first aspect of this application, a method for detectinga sent sequence is provided and applied to a receiver, where the methodincludes determining a maximum possible candidate value of each elementin N elements of a received element sequence to obtain N maximumpossible candidate values, where N is a positive integer, determiningstate sequences corresponding to the N maximum possible candidate valuesas reserved sequences to obtain N groups of reserved sequences,performing likelihood computation on the N groups of reserved sequences,and setting a reserved sequence that is in the N groups of reservedsequences and is most consistent with the element sequence as a detectedsent sequence.

With reference to the first aspect, in a first possible implementationof the first aspect, determining a maximum possible candidate value ofeach element in N elements of an element sequence to obtain N maximumpossible candidate values includes setting i to an integer from 1 to Nsequentially, and separately performing the following on an i^(th)element. Making a hard decision on the i^(th) element to obtain adecision value of the i^(th) element, where the i^(th) element is anelement in the N elements, obtaining a first Euclidean distance betweenan I component of the i^(th) element and an I component of the decisionvalue of the i^(th) element through computation according to the i^(th)element and the decision value of the i^(th) element, and determiningthe I component of the decision value of the i^(th) element as apossible value of the I component of the i^(th) element when the firstEuclidean distance is less than or equal to a first threshold, orsetting, according to a constellation corresponding to the i^(th)element, an I component value of one or two constellation points closestto the I component of the i^(th) element as a possible value of the Icomponent of the i^(th) element when the first Euclidean distance isgreater than the first threshold, where there are multiple constellationpoints in the constellation, and each constellation point represents apossible candidate value of the i^(th) element.

With reference to the first possible implementation of the first aspect,in a second possible implementation of the first aspect, afterdetermining the I component of the decision value of the i^(th) elementas a possible value of the I component of the i^(th) element or settingan I component value of one or two constellation points closest to the Icomponent of the i^(th) element as a possible value of the I componentof the i^(th) element, the method further includes obtaining a secondEuclidean distance between a Q component of the i^(th) element and a Qcomponent of the decision value of the i^(th) element throughcomputation, and determining the Q component of the decision value ofthe i^(th) element as a possible value of the Q component of the i^(th)element when the second Euclidean distance is less than or equal to asecond threshold, or setting, according to the constellation, a Qcomponent value of one or two constellation points closest to the Qcomponent of the i^(th) element as a possible value of the Q componentof the i^(th) element when the second Euclidean distance is greater thanthe second threshold.

With reference to the first aspect, in a third possible implementationof the first aspect, determining a maximum possible candidate value ofeach element in N elements of an element sequence to obtain N maximumpossible candidate values includes setting i to an integer from 1 to Nsequentially, and separately performing the following on an i^(th)element. Making a hard decision on an I component and a Q component ofthe i^(th) element to obtain a decision value of the I component of thei^(th) element and a decision value of the Q component of the i^(th)element, where the i^(th) element is an element in the N elements,obtaining a first Euclidean distance between the I component of thei^(th) element and the decision value of the I component of the i^(th)element through computation, and determining the decision value of the Icomponent of the i^(th) element as a possible value of the I componentof the i^(th) element when the first Euclidean distance is less than orequal to a first threshold, or setting, according to a constellationcorresponding to the i^(th) element, an I component value of one or twoconstellation points closest to the I component of the i^(th) element asa possible value of the I component of the i^(th) element when the firstEuclidean distance is greater than the first threshold, where there aremultiple constellation points in the constellation, and eachconstellation point represents a possible candidate value of the i^(th)element.

With reference to the third possible implementation of the first aspect,in a fourth possible implementation of the first aspect, afterdetermining the decision value of the I component of the i^(th) elementas a possible value of the I component of the i^(th) element or settingan I component value of one or two constellation points closest to the Icomponent of the i^(th) element as a possible value of the I componentof the i^(th) element, the method further includes obtaining a secondEuclidean distance between a Q component of the i^(th) element and adecision value of the Q component of the i^(th) element throughcomputation, and determining the decision value of the Q component ofthe i^(th) element as a possible value of the Q component of the i^(th)element when the second Euclidean distance is less than or equal to asecond threshold, or setting, according to the constellation, a Qcomponent value of one or two constellation points closest to the Qcomponent of the i^(th) element as a possible value of the Q componentof the i^(th) element when the second Euclidean distance is greater thanthe second threshold.

With reference to the second possible implementation of the first aspector the fourth possible implementation of the first aspect, in a fifthpossible implementation of the first aspect, determining a maximumpossible candidate value of each element in N elements of an elementsequence to obtain N maximum possible candidate values further includescombining the possible value of the I component of the i^(th) elementand the possible value of the Q component of the i^(th) element toobtain a maximum possible candidate value of the i^(th) element, andobtaining the N maximum possible candidate values.

According to a second aspect of this application, a receiver is providedand includes a receiving module configured to receive an elementsequence, and a detection module, connected to the receiving module, andconfigured to determine a maximum possible candidate value of eachelement in N elements of the element sequence to obtain N maximumpossible candidate values, determine state sequences corresponding tothe N maximum possible candidate values as reserved sequences to obtainN groups of reserved sequences, and perform likelihood computation onthe N groups of reserved sequences, and set a reserved sequence that isin the N groups of reserved sequences and is most consistent with theelement sequence as a detected sent sequence.

With reference to the second aspect, in a first possible implementationof the second aspect, the detection module is further configured to seti to an integer from 1 to N sequentially, and separately perform thefollowing on an i^(th) element. Making a hard decision on the i^(th)element to obtain a decision value of the i^(th) element, where thei^(th) element is an element in the N elements, obtaining a firstEuclidean distance between an I component of the i^(th) element and an Icomponent of the decision value of the i^(th) element throughcomputation according to the i^(th) element and the decision value ofthe i^(th) element, and determining the I component of the decisionvalue of the i^(th) element as a possible value of the I component ofthe i^(th) element when the first Euclidean distance is less than orequal to a first threshold, or setting, according to a constellationcorresponding to the i^(th) element, an I component value of one or twoconstellation points closest to the I component of the i^(th) element asa possible value of the I component of the i^(th) element when the firstEuclidean distance is greater than the first threshold, where there aremultiple constellation points in the constellation, and eachconstellation point represents a possible candidate value of the i^(th)element.

With reference to the first possible implementation of the secondaspect, in a second possible implementation of the second aspect, thedetection module is further configured to obtain a second Euclideandistance between a Q component of the i^(th) element and a Q componentof the decision value of the i^(th) element through computation afterdetermining the I component of the decision value of the i^(th) elementas the possible value of the I component of the i^(th) element orsetting the I component value of the one or two constellation pointsclosest to the I component of the i^(th) element as the possible valueof the I component of the i^(th) element, and determine the Q componentof the decision value of the i^(th) element as a possible value of the Qcomponent of the i^(th) element when the second Euclidean distance isless than or equal to a second threshold, or set, according to theconstellation, a Q component value of one or two constellation pointsclosest to the Q component of the i^(th) element as a possible value ofthe Q component of the i^(th) element when the second Euclidean distanceis greater than the second threshold.

With reference to the second aspect, in a third possible implementationof the second aspect, the detection module is further configured to seti to an integer from 1 to N sequentially, and separately perform thefollowing on an i^(th) element. Making a hard decision on an I componentand a Q component of the i^(th) element to obtain a decision value ofthe I component of the i^(th) element and a decision value of the Qcomponent of the i^(th) element, where the i^(th) element is an elementin the N elements, obtaining a first Euclidean distance between the Icomponent of the i^(th) element and the decision value of the Icomponent of the i^(th) element through computation, and determining thedecision value of the I component of the i^(th) element as a possiblevalue of the I component of the i^(th) element when the first Euclideandistance is less than or equal to a first threshold, or setting,according to a constellation corresponding to the i^(th) element, an Icomponent value of one or two constellation points closest to the Icomponent of the i^(th) element as a possible value of the I componentof the i^(th) element when the first Euclidean distance is greater thanthe first threshold, where there are multiple constellation points inthe constellation, and each constellation point represents a possiblecandidate value of the i^(th) element.

With reference to the third possible implementation of the secondaspect, in a fourth possible implementation of the second aspect, thedetection module is further configured to obtain a second Euclideandistance between a Q component of the i^(th) element and a decisionvalue of the Q component of the i^(th) element through computation afterdetermining the decision value of the I component of the i^(th) elementas the possible value of the I component of the i^(th) element orsetting the I component value of the one or two constellation pointsclosest to the I component of the i^(th) element as the possible valueof the I component of the i^(th) element, and determine the decisionvalue of the Q component of the i^(th) element as a possible value ofthe Q component of the i^(th) element when the second Euclidean distanceis less than or equal to a second threshold, or set, according to theconstellation, a Q component value of one or two constellation pointsclosest to the Q component of the i^(th) element as a possible value ofthe Q component of the i^(th) element when the second Euclidean distanceis greater than the second threshold.

With reference to the second possible implementation of the secondaspect or the fourth possible implementation of the second aspect, in afifth possible implementation of the second aspect, the detection moduleis further configured to combine the possible value of the I componentof the i^(th) element and the possible value of the Q component of thei^(th) element to obtain a maximum possible candidate value of thei^(th) element, and obtain the N maximum possible candidate values.

According to a third aspect of this application, a receiving device isprovided and includes a receiver configured to receive an elementsequence, a memory configured to store an instruction, where theinstruction includes determining a maximum possible candidate value ofeach element in N elements of the received element sequence to obtain Nmaximum possible candidate values, where N is a positive integer,determining state sequences corresponding to the N maximum possiblecandidate values as reserved sequences to obtain N groups of reservedsequences, performing likelihood computation on the N groups of reservedsequences, and setting a reserved sequence that is in the N groups ofreserved sequences and is most consistent with the element sequence as adetected sent sequence, and a processor configured to execute theinstruction.

With reference to the third aspect, in a first possible implementationof the third aspect, the instruction further includes setting i to aninteger from 1 to N sequentially, and separately performing thefollowing on an i^(th) element. Making a hard decision on the i^(th)element to obtain a decision value of the i^(th) element, where thei^(th) element is an element in the N elements, obtaining a firstEuclidean distance between an I component of the i^(th) element and an Icomponent of the decision value of the i^(th) element throughcomputation according to the i^(th) element and the decision value ofthe i^(th) element, and determining the I component of the decisionvalue of the i^(th) element as a possible value of the I component ofthe i^(th) element when the first Euclidean distance is less than orequal to a first threshold, or setting, according to a constellationcorresponding to the i^(th) element, an I component value of one or twoconstellation points closest to the I component of the i^(th) element asa possible value of the I component of the i^(th) element when the firstEuclidean distance is greater than the first threshold, where there aremultiple constellation points in the constellation, and eachconstellation point represents a possible candidate value of the i^(th)element.

With reference to the first possible implementation of the third aspect,in a second possible implementation of the third aspect, the instructionfurther includes obtaining a second Euclidean distance between a Qcomponent of the i^(th) element and a Q component of the decision valueof the i^(th) element through computation after determining the Icomponent of the decision value of the i^(th) element as the possiblevalue of the I component of the i^(th) element or setting the Icomponent value of the one or two constellation points closest to the Icomponent of the i^(th) element as the possible value of the I componentof the i^(th) element, and determining the Q component of the decisionvalue of the i^(th) element as a possible value of the Q component ofthe i^(th) element when the second Euclidean distance is less than orequal to a second threshold, or setting, according to the constellation,a Q component value of one or two constellation points closest to the Qcomponent of the i^(th) element as a possible value of the Q componentof the i^(th) element when the second Euclidean distance is greater thanthe second threshold.

With reference to the third aspect, in a third possible implementationof the third aspect, the instruction further includes setting i to aninteger from 1 to N sequentially, and separately performing thefollowing on an i^(th) element. Making a hard decision on an I componentand a Q component of the i^(th) element to obtain a decision value ofthe I component of the i^(th) element and a decision value of the Qcomponent of the i^(th) element, where the i^(th) element is an elementin the N elements, obtaining a first Euclidean distance between the Icomponent of the i^(th) element and the decision value of the Icomponent of the i^(th) element through computation, and determining thedecision value of the I component of the i^(th) element as a possiblevalue of the I component of the i^(th) element when the first Euclideandistance is less than or equal to a first threshold, or setting,according to a constellation corresponding to the i^(th) element, an Icomponent value of one or two constellation points closest to the Icomponent of the i^(th) element as a possible value of the I componentof the i^(th) element when the first Euclidean distance is greater thanthe first threshold, where there are multiple constellation points inthe constellation, and each constellation point represents a possiblecandidate value of the i^(th) element.

With reference to the third possible implementation of the third aspect,in a fourth possible implementation of the third aspect, the instructionfurther includes obtaining a second Euclidean distance between a Qcomponent of the i^(th) element and a decision value of the Q componentof the i^(th) element through computation after determining the decisionvalue of the I component of the i^(th) element as the possible value ofthe I component of the i^(th) element or setting the I component valueof the one or two constellation points closest to the I component of thei^(th) element as the possible value of the I component of the i^(th)element, and determining the decision value of the Q component of thei^(th) element as a possible value of the Q component of the i^(th)element when the second Euclidean distance is less than or equal to asecond threshold, or setting, according to the constellation, a Qcomponent value of one or two constellation points closest to the Qcomponent of the i^(th) element as a possible value of the Q componentof the i^(th) element when the second Euclidean distance is greater thanthe second threshold.

One or more technical solutions provided in embodiments of the presentdisclosure have at least the following technical effects or advantages.

In the embodiments of the present disclosure, a maximum possiblecandidate value of each element in N elements of a received elementsequence is determined such that N maximum possible candidate values areobtained, where N is a positive integer. State sequences correspondingto the N maximum possible candidate values are determined as reservedsequences such that N groups of reserved sequences are obtained, andlikelihood computation is performed on the N groups of reservedsequences, and a reserved sequence that is in the N groups of reservedsequences and is most consistent with the element sequence is used as adetected sent sequence. Therefore, screening is first performed on eachelement of the received element sequence, and a maximum possiblecandidate value is obtained from possible candidate values of eachelement. Finally, likelihood computation is performed only on a reservedstate corresponding to the maximum possible candidate value, and therebythe sent sequence is determined. However, computation is not performedon a state sequence corresponding to a non-maximum possible candidatevalue. It can be learned that, in comparison with the other approaches,a quantity of operations in the technical solutions provided by theembodiments of the present disclosure is reduced, and therefore,efficiency of detecting a sent sequence is improved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a flowchart of a method for detecting a sent sequenceaccording to an embodiment of the present disclosure;

FIG. 2 is a schematic diagram of a 16 QAM constellation andconstellation points of two original elements according to an embodimentof the present disclosure;

FIG. 3 is a schematic diagram of a constellation point and an I-axisaccording to an embodiment of the present disclosure;

FIG. 4 is a schematic structural diagram of a receiver according to anembodiment of the present disclosure; and

FIG. 5 is a schematic structural diagram of a receiving device accordingto an embodiment of the present disclosure.

DESCRIPTION OF EMBODIMENTS

The present disclosure provides a method for detecting a sent sequence,a receiver, and a receiving device in order to simplify an algorithm fordetecting a sent sequence and improve detection efficiency.

To resolve the foregoing technical problem, in the technical solutionsof the embodiments of the present disclosure, the method for detecting asent sequence in the present disclosure includes the following content.

In the embodiments of the present disclosure, a maximum possiblecandidate value of each element in N elements of a received elementsequence is determined such that N maximum possible candidate values areobtained, where N is a positive integer, state sequences correspondingto the N maximum possible candidate values are determined as reservedsequences such that N groups of reserved sequences are obtained, andlikelihood computation is performed on the N groups of reservedsequences, and a reserved sequence that is in the N groups of reservedsequences and is most consistent with the element sequence is used as adetected sent sequence. Therefore, screening is first performed on eachelement of the received element sequence, and a maximum possiblecandidate value is obtained from possible candidate values of eachelement. Finally, likelihood computation is performed only on a reservedstate corresponding to the maximum possible candidate value, and therebythe sent sequence is determined. However, computation is not performedon a state sequence corresponding to a non-maximum possible candidatevalue. It can be learned that, in comparison with the other approaches,a quantity of operations in the technical solutions provided by theembodiments of the present disclosure is reduced, and therefore,efficiency of detecting a sent sequence is improved.

To make the objectives, technical solutions, and advantages of theembodiments of the present disclosure clearer, the following clearlydescribes the technical solutions in the embodiments of the presentdisclosure with reference to the accompanying drawings in theembodiments of the present disclosure. The described embodiments aresome but not all of the embodiments of the present disclosure. All otherembodiments obtained by a person of ordinary skill in the art based onthe embodiments of the present disclosure without creative efforts shallfall within the protection scope of the present disclosure.

The term “and/or” in this specification describes only an associationrelationship for describing associated objects and represents that threerelationships may exist. For example, A and/or B may represent thefollowing three cases. Only A exists, both A and B exist, and only Bexists. In addition, the character “/” in this specification generallyindicates an “or” relationship between the associated objects.

The following describes the implementations of the present disclosure indetail with reference to accompanying drawings.

According to a first aspect of this application, a method for detectinga sent sequence is provided. Referring to FIG. 1, the method includesthe following steps.

Step S101: Determine a maximum possible candidate value of each elementin N elements of a received element sequence to obtain N maximumpossible candidate values.

Step S102: Determine state sequences corresponding to the N maximumpossible candidate values as reserved sequences to obtain N groups ofreserved sequences.

Step S103: Perform likelihood computation on the N groups of reservedsequences, and set a reserved sequence that is in the N groups ofreserved sequences and is most consistent with the element sequence as adetected sent sequence.

Further, in the technical field of this application, the elementsequence includes N elements, where N is a positive integer, forexample, 1, 30, or 392. Each element includes two components, namely, anI component and a Q component, represented in a form of a complexnumber. For example, if an element a1 in the form of a complex number is−3+1j, an I component of the element a1 is −3, and a Q component is 1.However, for each element, there are finite possible values of the Icomponent and possible values of the Q component. For example, in a 16QAM system, there are only four values, −3, −1, 1, and 3. Therefore, aquantity of candidate values of an element is finite. For example, thereare 16 values in total in 16 QAM. As shown in FIG. 2, in aconstellation, 16 candidate values of an element are shown by 16 blackpoints in FIG. 2. For another example, in 8 QAM, each element has eightcandidate values. Because the candidate values of each element in the 16QAM and 8 QAM systems are well-known, multiple candidate values of eachelement are not illustrated one by one herein.

Therefore, for any element in the element sequence, during sending at atransmit end, an actually sent value has only several finitepossibilities. In the several finite possibilities, a probability ofeach candidate value is not necessarily the same.

To reduce a quantity of operations of an MLSE-VA algorithm, in stepS101, the maximum possible candidate value of each element in the Nelements of the element sequence is first determined. In an embodimentof the present disclosure, two manners of determining a maximum possiblecandidate value from multiple candidate values of an element aredescribed in detail. A specific implementation process includes but isnot limited to the following two manners.

First Manner:

Because the element sequence includes multiple elements, and processingmanners of all elements are similar, for ease of description, thefollowing uses an i^(th) element as an example for description. In thefirst manner, step S101 further includes the following steps.

Step (11): Make a hard decision on the i^(th) element to obtain adecision value of the i^(th) element.

Step (12): Obtain a first Euclidean distance between an I component ofthe i^(th) element and an I component of the decision value of thei^(th) element through computation according to the i^(th) element andthe decision value of the i^(th) element.

Step (13): Determine the I component of the decision value of the i^(th)element as a possible value of the I component of the i^(th) elementwhen the first Euclidean distance is less than or equal to a firstthreshold, or set, according to a constellation corresponding to thei^(th) element, an I component value of one or two constellation pointsclosest to the I component of the i^(th) element as a possible value ofthe I component of the i^(th) element when the first Euclidean distanceis greater than the first threshold.

Step (14): Obtain a second Euclidean distance between a Q component ofthe i^(th) element and a Q component of the decision value of the i^(th)element through computation.

Step (15): Determine the Q component of the decision value of the i^(th)element as a possible value of the Q component of the i^(th) elementwhen the second Euclidean distance is less than or equal to a secondthreshold, or set, according to the constellation, a Q component valueof one or two constellation points closest to the Q component of thei^(th) element as a possible value of the Q component of the i^(th)element when the second Euclidean distance is greater than the secondthreshold.

In order to determine a maximum possible candidate value of the i^(th)element of the element sequence, in step (11), first, a hard decision ismade on the i^(th) element. In this embodiment of the presentdisclosure, the hard decision is to determine a value of a constellationpoint closest to a constellation point of an original element in theconstellation. For ease of description, the following uses a receiver inthe 16 QAM system as an example for description. Assuming that anoriginal constellation point p1 of the i^(th) element is (−2, 0.2), alocation of the point p1 is shown in FIG. 2. Through computation, p1 isclosest to a point (−1, 1) in the constellation, and therefore, adecision value of the point p1 is −1+1j.

In this embodiment of the present disclosure, the foregoing process ofobtaining the decision value of the i^(th) element includes computingthe Euclidean distance between the original constellation point of thei^(th) element and each constellation point. A closest constellationpoint is a constellation point closest to the original constellationpoint of the element, and a value of the closest constellation point isthe decision value of the i^(th) element.

Next, in step (12), the first Euclidean distance between the I componentof the i^(th) element and the I component of the decision value of thei^(th) element is obtained according to the i^(th) th element and thedecision value of the i^(th) element. In this embodiment of the presentdisclosure, the first Euclidean distance is also computed using theEuclidean distance algorithm. For example, the first Euclidean distancebetween the I component of the point p1 and the I component of thedecision value is:

√{square root over ([−2−(−1)]²)}=1.

Then in step (13), it is necessary to compare the first Euclideandistance with the first threshold. The first threshold is a positivenumber, for example, 1, 0.5, or 0.7. The first threshold may be setaccording to complexity of the algorithm and a performance requirement.For example, precision of detecting a sent sequence according to thefirst threshold 0.5 is higher than precision of detection when the firstthreshold is 1. A person of ordinary skill in the art may performsetting according to an actual requirement, and this is not limited inthis application.

When the first Euclidean distance is less than or equal to the firstthreshold, the I component of the decision value of the i^(th) elementis determined as a possible value of the I component of the i^(th)element. However, when the first Euclidean distance is greater than thefirst threshold, an I component of one or two constellation pointsclosest to the I component of the i^(th) element in the 16 constellationpoints in the constellation is used as a possible value of the Icomponent of the element.

Still using the foregoing example for description, assuming that thefirst threshold in this case is 0.7, the first Euclidean distance isgreater than the first threshold. In this case, the I component of oneor two constellation points closest to the I component of p1 in the 16constellation points in the constellation is used as a possible value ofthe I component of p1. As shown in FIG. 2 and FIG. 3, the I component ofthe point p1 is −2, and p1 is between −1 and −3 in an I-axis direction,and is one unit length away from both −1 and −3. Therefore, −1+1j and−3+1j are two constellation points closest to the I component of thepoint p1. In this case, I components of −1+1j and −3+1j are used aspossible values of the I component of the point p1. Therefore, possiblevalues of the I component of the point p1 are −1 and −3.

The constellation includes multiple constellation points. For example, 8QAM includes eight constellation points, and 16 QAM includes 16constellation points. Each constellation point represents a possiblecandidate value of the i^(th) element.

The step (14) is performed to obtain the second Euclidean distancebetween the Q component of the i^(th) element and the Q component of thedecision value of the i^(th) element. In this embodiment of the presentdisclosure, the second Euclidean distance is similar to the firstEuclidean distance, and is also computed using the Euclidean distancealgorithm. For example, the second Euclidean distance between the Qcomponent of the point p1 and the Q component of the decision value is:

√{square root over ((0.2−1)²)}=0.8.

Then in step (15), it is necessary to compare the second Euclideandistance with the second threshold. The second threshold is also apositive number, for example, 1, 0.5, or 0.7. The second threshold mayalso be set according to complexity of the algorithm and a performancerequirement. In addition, in a specific implementation process, thesecond threshold and the first threshold may be set to a same value, ormay be set to different values. This is not limited in this application.

Similar to processing of the I component of the i^(th) element, when thesecond Euclidean distance is less than or equal to the second threshold,the Q component of the decision value of the i^(th) element isdetermined as a possible value of the Q component of the i^(th) element.However, when the second Euclidean distance is greater than the secondthreshold, a Q component of one or two constellation points closest tothe Q component of the i^(th) element in the 16 constellation points inthe constellation is used as a possible value of the Q component of thei^(th) element.

Still using the foregoing example for description, assuming that boththe second threshold and the first threshold in this case are 0.7, thesecond Euclidean distance is greater than the second threshold. As shownin FIG. 2, −1+1j, −3+1j, −1−1j, and −3−1j are four constellation pointsclosest to the Q component of the point p1. In this case, Q componentsof the four constellation points are used as possible values of the Qcomponent of the point p1. Therefore, possible values of the Q componentof the point p1 are 1 and −1.

When the first Euclidean distance is greater than the first threshold,and the I component of the i^(th) element is less than or equal to aminimum value on an I-axis of the constellation or is greater than orequal to a maximum value on the I-axis, in this case, the I component ofthe i^(th) element is only close to a constellation point with themaximum value or the minimum value on the I-axis, and therefore, thereis only one possible value of the I component of the i^(th) element.However, when the I component of the i^(th) element is between twovalues on the I-axis, there are two possible values of the I componentof the i^(th) element. However, when the first Euclidean distance isless than or equal to the first threshold, the possible value of the Icomponent of the i^(th) element may be only a decision value of the Icomponent or the I component of the decision value. The possible valueof the Q component of the i^(th) element is similar to this. Therefore,a quantity of possible values of the I component of the i^(th) elementor possible values of the Q component of the i^(th) element is 1 or 2.

In a specific implementation process, steps (12) to (13) may be firstperformed and then steps (14) to (15) are performed, that is, first, thepossible value of the I component is obtained, and then the possiblevalue of the Q component is obtained. Alternatively, steps (14) to (15)may be first performed and then steps (12) to (13) are performed, thatis, first, the possible value of the Q component is obtained, and thenthe possible value of the I component is obtained. Alternatively, steps(14) to (15) and steps (12) to (13) may be performed simultaneously, andpossible values of the two components are obtained simultaneously. Aperson skilled in the art can make a selection according to an actualrequirement, and this is not limited in this application.

Second Manner:

In the second manner, step S101 further includes the following steps.

Step (21): Make a hard decision on an I component and a Q component ofthe i^(th) element to obtain a decision value of the I component of thei^(th) element and a decision value of the Q component of the i^(th)element.

Step (22): Obtain a first Euclidean distance between the I component ofthe i^(th) element and the decision value of the I component of thei^(th) element through computation.

Step (23): Determine the decision value of the I component of the i^(th)element as a possible value of the I component of the i^(th) elementwhen the first Euclidean distance is less than or equal to a firstthreshold, or set, according to a constellation corresponding to thei^(th) element, an I component value of one or two constellation pointsclosest to the I component of the i^(th) element as a possible value ofthe I component of the i^(th) element when the first Euclidean distanceis greater than the first threshold, where there are multipleconstellation points in the constellation, and each constellation pointrepresents a possible candidate value of the i^(th) element.

Step (24): Obtain a second Euclidean distance between a Q component ofthe i^(th) element and a decision value of the Q component of the i^(th)element through computation.

Step (25): Determine the decision value of the Q component of the i^(th)element as a possible value of the Q component of the i^(th) elementwhen the second Euclidean distance is less than or equal to a secondthreshold, or set, according to the constellation, a Q component valueof one or two constellation points closest to the Q component of thei^(th) element as a possible value of the Q component of the i^(th)element when the second Euclidean distance is greater than the secondthreshold.

In order to determine a maximum possible candidate value of the i^(th)element of the element sequence, in step (21), first, a hard decision ismade on the I component and the Q component of the i^(th) element.Similar to the first manner, the hard decision is to determine aconstellation point closest to a constellation point of an originalelement in the constellation. A difference lies in that, only a distancebetween constellation points in an I-axis direction is considered whenthe I component of the i^(th) element is decided, and only a distancebetween constellation points in a Q-axis direction is considered whenthe Q component of the i^(th) element is decided. It is assumed that alocation of an original constellation point p2 (−2.88, −3.6) of thei^(th) element is shown in FIG. 2. −2.88 is closest to −3 in the I-axisdirection, and therefore, a decision value of the I component of thepoint p2 is −3. Likewise, −3.6 is closest to −3 in the Q-axis direction,and therefore, a decision value of the Q component of the point p2 isalso −3.

Next, the first Euclidean distance between the decision value of the Icomponent of the i^(th) element and the I component of the i^(th)element is obtained:

√{square root over ([−2.99−(−3)]²)}=0.12, and

the second Euclidean distance between the decision value of the Qcomponent of the i^(th) element and the Q component of the i^(th)element is obtained:

√{square root over ([−3.6−(−3)]²)}=0.6.

Next, similar to the first manner, the second manner is to determine thepossible value of the I component of the i^(th) element and the possiblevalue of the Q component by comparing the first Euclidean distance withthe first threshold and comparing the second Euclidean distance with thesecond threshold. For a detailed description, reference may be made tothe first manner. Details are not described again herein.

The example in which p2 is −2.88−3.6j is still used for description.Assuming that the first threshold in this case is 0.5, and that thesecond threshold is 0.7, the first Euclidean distance is less than thefirst threshold, and the second Euclidean distance is also less than thesecond threshold. Therefore, the possible value of the I component ofthe element p2 and the possible value of the Q component are both −3.

In a specific implementation process, the first manner may be used toobtain possible values of the two components, or the second manner maybe used to obtain possible values of the two components. A person ofordinary skill in the art may perform setting according to an actualrequirement, and this is not limited in this application.

Further, in this embodiment of the present disclosure, after thepossible values of the two components are obtained, step S101 furtherincludes combining the possible value of the I component of the i^(th)element and the possible value of the Q component of the i^(th) elementto obtain a maximum possible candidate value of the i^(th) element, andobtaining the N maximum possible candidate values.

Further, an original element is represented in the form of a complexnumber. Therefore, after the possible value of the I component of thei^(th) element and the possible value of the Q component of the i^(th)element are obtained, the values are combined still in the form of acomplex number, and the maximum possible candidate value of the i^(th)element may be obtained, and further, the maximum possible candidatevalues of the N elements are obtained.

Still using the foregoing example for description, an original value ofthe element p1 is −2+0.2j, possible values of the I component are −1 and−3, and possible values of the Q component are 1 and −1. Therefore, theelement p1 has four maximum possible candidate values, which are −1+1j,−1−1j, −3+1j, and −3−1j respectively.

An original value of the element p2 is −2.88−3.6j, a possible value ofthe I component is −3, and a possible value of the Q component is −3.Therefore, the element p1 has only one maximum possible candidate value,namely, −3−3j.

In this embodiment of the present disclosure, if possible values of thetwo components are both decision values of corresponding components orcomponents of decision values, after the possible values of the twocomponents are combined, the i^(th) element has only one maximumpossible candidate value. If a possible value of one component is adecision value, but a possible value of the other component is acomponent value of a constellation point closest to the component of thei^(th) element, after the possible values of the two components arecombined, the i^(th) element also has only one maximum possiblecandidate value.

When a possible value of one component of the i^(th) element is adecision value or a component value of a closest constellation point,but possible values of the other component are component values of twoclosest constellation points, after the possible values of the twocomponents are combined, the i^(th) element has two maximum possiblecandidate values.

When a possible value of one component of the i^(th) element is adecision value or a component value of a closest constellation point,but possible values of the other component are component values of threeclosest constellation points (for example, a receiver in the 8 QAMsystem), after the possible values of the two components are combined,the i^(th) element has three maximum possible candidate values.

Finally, when the two components both have two possible values, afterthe possible values of the two components are combined, the i^(th)element has four maximum possible candidate values.

After the maximum possible candidate value of each element is obtained,the N maximum possible candidate values may be further obtained.

Next, in step S102, the state sequences corresponding to the N maximumpossible candidate values are determined as reserved sequences, and theN groups of reserved sequences are further obtained. Further, eachelement has multiple possible values, for example, in 16 QAM, eachelement has 16 possible values, and each value may correspond tomultiple states. Therefore, possible values of all elements correspondto a large quantity of states. In this embodiment of the presentdisclosure in order to reduce a quantity of operations of MLSE-VA, onlystate sequences corresponding to the N maximum possible candidate valuesare reserved as reserved sequences, but state sequences corresponding tonon-maximum possible candidate values are not processed any longer insubsequent computation.

For example, for the element sequence including the element p1, stepS101 is performed to obtain the maximum possible candidate value of p1,−1+1j, −1−1j, −3+1j, or −3−1j. In step S102, only a state sequencecorresponding to −1+1j, −1−1j, −3+1j, or −3−1j is reserved as a reservedsequence. However, all state sequences corresponding to other possiblevalues of p1, namely, −3+3j, −1+3j, 3+3j, 1+1j, 3+1j, 1−1, 3−1, −3−j,−1−3j, −1−3j, and 3+3j, are deleted, and are no longer considered orcomputed subsequently.

In addition to the element p1, the element sequence further includesother elements. The foregoing processing is performed on each element,and only a state sequence corresponding to the maximum possiblecandidate value of each element is reserved as a reserved sequence.Therefore, after such processing, likelihood computation is performed ononly the reserved sequence in step S103. Therefore, in comparison withthe other approaches in which likelihood computation is performed on allstate sequences, a quantity of operations is reduced.

In step S103, likelihood computation is performed on the N groups ofreserved sequences to obtain likelihood between the reserved sequencesand the element sequence. Finally, in the N groups of reservedsequences, according to the likelihood between each group of reservedsequences and the element sequence, a group of reserved sequences havingmaximum likelihood with the element sequence is used as the detectedsent sequence.

A specific process of performing likelihood computation in step S103 issimilar to that in the other approaches, and is not described herein.

Further, when likelihood computation is performed in step S103 in orderto reduce impact caused by an error of the decision value in step S101on a result, a likelihood result further needs to be multiplied by acorresponding weighting factor. Further, the weighting factor isdetermined according to the first Euclidean distance and the secondEuclidean distance. The weighting factor is smaller when the firstEuclidean distance and the second Euclidean distance are greater. Theweighting factor is greater when the first Euclidean distance and thesecond Euclidean distance are smaller. For example, for the foregoingelement p1, when the first Euclidean distance is 1, and the secondEuclidean distance does not exceed 0.8, both 1 and 0.8 are large.Therefore, a likelihood result of a reserved state corresponding to themaximum possible candidate value of the element p1 may be multiplied bya small weighting factor such as 0.1 or 0.2. The first Euclideandistance and the second Euclidean distance of the element p2 are 0.12and 0.6, and are relatively small, and therefore, 0.5, 0.8, 1, or thelike may be selected as a corresponding weighting factor.

In a specific implementation process, a person skilled in the art mayset the weighting factor according to a preset rule. For example, forthe Euclidean distance in a range from 0 to 1, the weighting factor isset to 1. For the Euclidean distance between 1 and 3, the weightingfactor is set to 0.5. For the Euclidean distance between 3 and 6, theweighting factor is set to 0.1. For the Euclidean distance of 6, theweighting factor is set to 0.01, and so on. This is not limited in thisapplication.

According to a second aspect of this application, a receiver isprovided, and as shown in FIG. 4, includes a receiving module 201configured to receive an element sequence, and a detection module 202,connected to the receiving module 201, and configured to determine amaximum possible candidate value of each element in N elements of theelement sequence to obtain N maximum possible candidate values,determine state sequences corresponding to the N maximum possiblecandidate values as reserved sequences to obtain N groups of reservedsequences, and perform likelihood computation on the N groups ofreserved sequences, and set a reserved sequence that is in the N groupsof reserved sequences and is most consistent with the element sequenceas a detected sent sequence.

In this embodiment of the present disclosure, the receiver may furtherinclude a preprocessing module 203. The receiving module 201 isconnected to the detection module 202 by the preprocessing module 203.The preprocessing module 203 is configured to perform preprocessing onthe element sequence, including but not limited to digital-to-analogconversion, equalization processing, filtering, and the like.

In this embodiment of the present disclosure, there are twoimplementations of obtaining the N maximum possible candidate values.The detection module 202 may also have two implementations.

In the first manner, the detection module 202 is configured to set i toan integer from 1 to N sequentially, and separately perform thefollowing on an i^(th) element. Making a hard decision on the i^(th)element to obtain a decision value of the i^(th) element, where thei^(th) element is an element in the N elements, obtaining a firstEuclidean distance between an I component of the i^(th) element and an Icomponent of the decision value of the i^(th) element throughcomputation according to the i^(th) element and the decision value ofthe i^(th) element, and determining the I component of the decisionvalue of the i^(th) element as a possible value of the I component ofthe i^(th) element when the first Euclidean distance is less than orequal to a first threshold, or setting, according to a constellationcorresponding to the i^(th) element, an I component value of one or twoconstellation points closest to the I component of the i^(th) element asa possible value of the I component of the i^(th) element when the firstEuclidean distance is greater than the first threshold, where there aremultiple constellation points in the constellation, and eachconstellation point represents a possible candidate value of the i^(th)element.

The detection module 202 is further configured to obtain a secondEuclidean distance between a Q component of the i^(th) element and a Qcomponent of the decision value of the i^(th) element throughcomputation after determining the I component of the decision value ofthe i^(th) element as the possible value of the I component of thei^(th) element or using the I component value of the one or twoconstellation points closest to the I component of the i^(th) element asthe possible value of the I component of the i^(th) element, anddetermine the Q component of the decision value of the i^(th) element asa possible value of the Q component of the i^(th) element when thesecond Euclidean distance is less than or equal to a second threshold,or set, according to the constellation, a Q component value of one ortwo constellation points closest to the Q component of the i^(th)element as a possible value of the Q component of the i^(th) elementwhen the second Euclidean distance is greater than the second threshold.

In the second manner, the detection module 202 is further configured toset i to an integer from 1 to N sequentially, and separately perform thefollowing on an i^(th) element. Making a hard decision on an I componentand a Q component of the i^(th) element to obtain a decision value ofthe I component of the i^(th) element and a decision value of the Qcomponent of the i^(th) element, where the i^(th) element is an elementin the N elements, obtaining a first Euclidean distance between the Icomponent of the i^(th) element and the decision value of the Icomponent of the i^(th) element through computation, and determining thedecision value of the I component of the i^(th) element as a possiblevalue of the I component of the i^(th) element when the first Euclideandistance is less than or equal to a first threshold, or setting,according to a constellation corresponding to the i^(th) element, an Icomponent value of one or two constellation points closest to the Icomponent of the i^(th) element as a possible value of the I componentof the i^(th) element when the first Euclidean distance is greater thanthe first threshold, where there are multiple constellation points inthe constellation, and each constellation point represents a possiblecandidate value of the i^(th) element.

Further, the detection module 202 is further configured to obtain asecond Euclidean distance between a Q component of the i^(th) elementand a decision value of the Q component of the i^(th) element throughcomputation after determining the decision value of the I component ofthe i^(th) element as the possible value of the I component of thei^(th) element or setting the I component value of the one or twoconstellation points closest to the I component of the i^(th) element asthe possible value of the I component of the i^(th) element, anddetermine the decision value of the Q component of the i^(th) element asa possible value of the Q component of the i^(th) element when thesecond Euclidean distance is less than or equal to a second threshold,or set, according to the constellation, a Q component value of one ortwo constellation points closest to the Q component of the i^(th)element as a possible value of the Q component of the i^(th) elementwhen the second Euclidean distance is greater than the second threshold.

Optionally, regardless of which implementation is used to process thei^(th) element, the detection module 202 is further configured tocombine the possible value of the I component of the i^(th) element andthe possible value of the Q component of the i^(th) element to obtain amaximum possible candidate value of the i^(th) element, and obtain the Nmaximum possible candidate values.

According to a third aspect of this application, a receiving device isprovided, and as shown in FIG. 5, includes a receiver 301 configured toreceive an element sequence, a memory 302 configured to store aninstruction, where the instruction includes determining a maximumpossible candidate value of each element in N elements of the receivedelement sequence to obtain N maximum possible candidate values, where Nis a positive integer, determining state sequences corresponding to theN maximum possible candidate values as reserved sequences to obtain Ngroups of reserved sequences, performing likelihood computation on the Ngroups of reserved sequences, and setting a reserved sequence that is inthe N groups of reserved sequences and is most consistent with theelement sequence as a detected sent sequence, and a processor 303configured to execute the instruction.

Optionally, the instruction further includes setting i to an integerfrom 1 to N sequentially, and separately performing the following on ani^(th) element. Making a hard decision on the i^(th) element to obtain adecision value of the i^(th) element, where the i^(th) element is anelement in the N elements, obtaining a first Euclidean distance betweenan I component of the i^(th) th element and an I component of thedecision value of the 1 element through computation according to thei^(th) element and the decision value of the i^(th) element, anddetermining the I component of the decision value of the i^(th) elementas a possible value of the I component of the i^(th) element when thefirst Euclidean distance is less than or equal to a first threshold, orsetting, according to a constellation corresponding to the i^(th)element, an I component value of one or two constellation points closestto the I component of the i^(th) element as a possible value of the Icomponent of the i^(th) element when the first Euclidean distance isgreater than the first threshold, where there are multiple constellationpoints in the constellation, and each constellation point represents apossible candidate value of the i^(th) element.

The instruction further includes obtaining a second Euclidean distancebetween a Q component of the i^(th) element and a Q component of thedecision value of the i^(th) element through computation afterdetermining the I component of the decision value of the i^(th) elementas the possible value of the I component of the i^(th) element or usingthe I component value of the one or two constellation points closest tothe I component of the i^(th) element as the possible value of the Icomponent of the i^(th) element, and determining the Q component of thedecision value of the i^(th) element as a possible value of the Qcomponent of the i^(th) element when the second Euclidean distance isless than or equal to a second threshold, or setting, according to theconstellation, a Q component value of one or two constellation pointsclosest to the Q component of the i^(th) element as a possible value ofthe Q component of the i^(th) element when the second Euclidean distanceis greater than the second threshold.

Optionally, the instruction includes setting i to an integer from 1 to Nsequentially, and separately performing the following on an i^(th)element. Making a hard decision on an I component and a Q component ofthe i^(th) element to obtain a decision value of the I component of thei^(th) element and a decision value of the Q component of the i^(th)element, where the i^(th) element is an element in the N elements,obtaining a first Euclidean distance between the I component of thei^(th) element and the decision value of the I component of the i^(th)element through computation, and determining the decision value of the Icomponent of the i^(th) element as a possible value of the I componentof the i^(th) element when the first Euclidean distance is less than orequal to a first threshold, or setting, according to a constellationcorresponding to the i^(th) element, an I component value of one or twoconstellation points closest to the I component of the i^(th) element asa possible value of the I component of the i^(th) element when the firstEuclidean distance is greater than the first threshold, where there aremultiple constellation points in the constellation, and eachconstellation point represents a possible candidate value of the i^(th)element.

The instruction further includes obtaining a second Euclidean distancebetween a Q component of the i^(th) element and a decision value of theQ component of the i^(th) element through computation after determiningthe decision value of the I component of the i^(th) element as thepossible value of the I component of the i^(th) element or using the Icomponent value of the one or two constellation points closest to the Icomponent of the i^(th) element as the possible value of the I componentof the i^(th) element, and determining the decision value of the Qcomponent of the i^(th) element as a possible value of the Q componentof the i^(th) element when the second Euclidean distance is less than orequal to a second threshold, or setting, according to the constellation,a Q component value of one or two constellation points closest to the Qcomponent of the i^(th) element as a possible value of the Q componentof the i^(th) element when the second Euclidean distance is greater thanthe second threshold.

In FIG. 5, for a bus architecture (represented by a bus 300), the bus300 may include any quantity of interconnecting buses and bridges, andthe bus 300 interconnects various circuits of one or more processorsrepresented by the processor 303 and a memory represented by the memory302. A bus interface 304 provides an interface between the bus 300 andthe receiver 301. The bus 300 may further interconnect various othercircuits such as a peripheral device, a voltage regulator, and a powermanagement circuit. These are all well known, and therefore are notfurther described in the specification.

The processor 303 is responsible for managing the bus 300 and generalprocessing. The memory 302 may be configured to store data used when theprocessor 303 performs an operation.

Various manners and specific examples in the process of detecting a sentsequence in the foregoing embodiments are also applicable to thereceiving device in this embodiment. According to the detaileddescriptions about the process of detecting a sent sequence and theexecution process of the receiver, a person skilled in the art mayclearly know the implementation method of the receiving device in thisembodiment. Therefore, for brevity of the specification, details are notdescribed again herein.

One or more technical solutions provided in the embodiments of thepresent disclosure have at least the following technical effects oradvantages.

In the embodiments of the present disclosure, a maximum possiblecandidate value of each element in N elements of a received elementsequence is determined such that N maximum possible candidate values areobtained, where N is a positive integer, state sequences correspondingto the N maximum possible candidate values are determined as reservedsequences such that N groups of reserved sequences are obtained, andlikelihood computation is performed on the N groups of reservedsequences, and a reserved sequence that is in the N groups of reservedsequences and is most consistent with the element sequence is used as adetected sent sequence. Therefore, screening is first performed on eachelement of the received element sequence, and a maximum possiblecandidate value is obtained from possible candidate values of eachelement. Finally, likelihood computation is performed only on a reservedstate corresponding to the maximum possible candidate value, and therebythe sent sequence is determined. However, computation is not performedon a state sequence corresponding to a non-maximum possible candidatevalue. It can be learned that, in comparison with the other approaches,a quantity of operations in the technical solutions provided by theembodiments of the present disclosure is reduced, and therefore,efficiency of detecting a sent sequence is improved.

A person skilled in the art should understand that the embodiments ofthe present disclosure may be provided as a method, a system, or acomputer program product. Therefore, the present disclosure may use aform of hardware only embodiments, software only embodiments, orembodiments with a combination of software and hardware. Moreover, thepresent disclosure may use a form of a computer program product that isimplemented on one or more computer-usable storage media (including butnot limited to a disk memory, a compact disc read only memory (CD-ROM),an optical memory, and the like) that include computer-usable programcode.

The present disclosure is described with reference to the flowchartsand/or block diagrams of the method, the device (system), and thecomputer program product according to the embodiments of the presentdisclosure. It should be understood that computer program instructionsmay be used to implement each process and/or each block in theflowcharts and/or the block diagrams and a combination of a processand/or a block in the flowcharts and/or the block diagrams. Thesecomputer program instructions may be provided for a general-purposecomputer, a dedicated computer, an embedded processor, or a processor ofany other programmable data processing device to generate a machine suchthat the instructions executed by a computer or a processor of any otherprogrammable data processing device generate an apparatus forimplementing a specific function in one or more processes in theflowcharts and/or in one or more blocks in the block diagrams.

These computer program instructions may be stored in a computer readablememory that can instruct the computer or any other programmable dataprocessing device to work in a specific manner such that theinstructions stored in the computer readable memory generate an artifactthat includes an instruction apparatus. The instruction apparatusimplements a specific function in one or more processes in theflowcharts and/or in one or more blocks in the block diagrams.

These computer program instructions may be loaded onto a computer oranother programmable data processing device such that a series ofoperations and steps are performed on the computer or the otherprogrammable device, thereby generating computer-implemented processing.Therefore, the instructions executed on the computer or the otherprogrammable device provide steps for implementing a specific functionin one or more processes in the flowcharts and/or in one or more blocksin the block diagrams.

Obviously, a person skilled in the art can make various modificationsand variations to the present disclosure without departing from thespirit and scope of the present disclosure. The present disclosure isintended to cover these modifications and variations provided that theyfall within the scope of protection defined by the following claims andtheir equivalent technologies.

What is claimed is:
 1. A method for detecting a sent sequence, appliedto a receiver, comprising: determining a maximum possible candidatevalue of each element in N elements of a received element sequence toobtain N maximum possible candidate values, wherein N is a positiveinteger; determining state sequences corresponding to the N maximumpossible candidate values as reserved sequences to obtain N groups ofreserved sequences; performing likelihood computation on the N groups ofreserved sequences; and setting a reserved sequence that is in the Ngroups of reserved sequences and is most consistent with the elementsequence as a detected sent sequence.
 2. The method according to claim1, wherein determining the maximum possible candidate value of eachelement in the N elements of the received element sequence to obtain theN maximum possible candidate values comprises setting i to an integerfrom 1 to N sequentially, and separately performing the following on ani^(th) element: making a hard decision on the i^(th) element to obtain adecision value of the i^(th) element, wherein the i^(th) element is anelement in the N elements; obtaining a first Euclidean distance betweenan I component of the i^(th) element and an I component of the decisionvalue of the i^(th) element through computation according to the i^(th)element and the decision value of the i^(th) element; determining the Icomponent of the decision value of the i^(th) element as a possiblevalue of the I component of the i^(th) element when the first Euclideandistance is less than or equal to a first threshold; and setting,according to a constellation corresponding to the i^(th) element, an Icomponent value of one or two constellation points closest to the Icomponent of the i^(th) element as the possible value of the I componentof the i^(th) element when the first Euclidean distance is greater thanthe first threshold, wherein there is a plurality of constellationpoints in the constellation, and wherein each constellation pointrepresents a possible candidate value of the i^(th) element.
 3. Themethod according to claim 2, wherein after determining the I componentof the decision value of the i^(th) element as the possible value of theI component of the i^(th) element or after setting the I component valueof one or two constellation points closest to the I component of thei^(th) element as the possible value of the I component of the i^(th)element, the method further comprises: obtaining a second Euclideandistance between a Q component of the i^(th) element and a Q componentof the decision value of the i^(th) element through computation;determining the Q component of the decision value of the i^(th) elementas a possible value of the Q component of the i^(th) element when thesecond Euclidean distance is less than or equal to a second threshold;and setting, according to the constellation, a Q component value of oneor two constellation points closest to the Q component of the i^(th)element as the possible value of the Q component of the i^(th) elementwhen the second Euclidean distance is greater than the second threshold.4. The method according to claim 1, wherein determining the maximumpossible candidate value of each element in the N elements of thereceived element sequence to obtain the N maximum possible candidatevalues comprises setting i to an integer from 1 to N sequentially, andseparately performing the following on an i^(th) element: making a harddecision on an I component and a Q component of the i^(th) element toobtain a decision value of the I component of the i^(th) element and adecision value of the Q component of the i^(th) element, wherein thei^(th) element is an element in the N elements; obtaining a firstEuclidean distance between the I component of the i^(th) element and thedecision value of the I component of the i^(th) element throughcomputation; determining the decision value of the I component of thei^(th) element as a possible value of the I component of the i^(th)element when the first Euclidean distance is less than or equal to afirst threshold; and setting, according to a constellation correspondingto the i^(th) element, an I component value of one or two constellationpoints closest to the I component of the i^(th) element as the possiblevalue of the I component of the i^(th) element when the first Euclideandistance is greater than the first threshold, wherein there is aplurality of constellation points in the constellation, and wherein eachconstellation point represents a possible candidate value of the i^(th)element.
 5. The method according to claim 4, wherein after determiningthe decision value of the I component of the i^(th) element as thepossible value of the I component of the i^(th) element or setting the Icomponent value of one or two constellation points closest to the Icomponent of the i^(th) element as the possible value of the I componentof the i^(th) element, the method further comprises: obtaining a secondEuclidean distance between the Q component of the i^(th) element and thedecision value of the Q component of the i^(th) element throughcomputation; determining the decision value of the Q component of thei^(th) element as a possible value of the Q component of the i^(th)element when the second Euclidean distance is less than a secondthreshold; and setting, according to the constellation, a Q componentvalue of one or two constellation points closest to the Q component ofthe i^(th) element as the possible value of the Q component of thei^(th) element when the second Euclidean distance is greater than thesecond threshold.
 6. The method according to claim 4, wherein afterdetermining the decision value of the I component of the i^(th) elementas the possible value of the I component of the i^(th) element orsetting the I component value of one or two constellation points closestto the I component of the i^(th) element as the possible value of the Icomponent of the i^(th) element, the method further comprises: obtaininga second Euclidean distance between the Q component of the i^(th)element and the decision value of the Q component of the i^(th) elementthrough computation; determining the decision value of the Q componentof the i^(th) element as a possible value of the Q component of thei^(th) element when the second Euclidean distance is equal to a secondthreshold; and setting, according to the constellation, a Q componentvalue of one or two constellation points closest to the Q component ofthe i^(th) element as the possible value of the Q component of thei^(th) element when the second Euclidean distance is greater than thesecond threshold.
 7. The method according to claim 3, whereindetermining the maximum possible candidate value of each element in theN elements of the received element sequence to obtain the N maximumpossible candidate values comprises: combining the possible value of theI component of the i^(th) element and the possible value of the Qcomponent of the i^(th) element to obtain a maximum possible candidatevalue of the i^(th) element; and obtaining the N maximum possiblecandidate values.
 8. A receiver, comprising: a transceiver configured toreceive an element sequence; and a processor connected to thetransceiver and configured to: determine a maximum possible candidatevalue of each element in N elements of the element sequence to obtain Nmaximum possible candidate values; determine state sequencescorresponding to the N maximum possible candidate values as reservedsequences to obtain N groups of reserved sequences; perform likelihoodcomputation on the N groups of reserved sequences; and set a reservedsequence that is in the N groups of reserved sequences and is mostconsistent with the element sequence as a detected sent sequence.
 9. Thereceiver according to claim 8, wherein the processor is furtherconfigured to set i to an integer from 1 to N sequentially, andseparately perform the following on an i^(th) element: make a harddecision on the i^(th) element to obtain a decision value of the i^(th)element, wherein the i^(th) element is an element in the N elements;obtain a first Euclidean distance between an I component of the i^(th)element and an I component of the decision value of the i^(th) elementthrough computation according to the i^(th) element and the decisionvalue of the i^(th) element; determine the I component of the decisionvalue of the i^(th) element as a possible value of the I component ofthe i^(th) element when the first Euclidean distance is less than orequal to a first threshold; and set, according to a constellationcorresponding to the i^(th) element, an I component value of one or twoconstellation points closest to the I component of the i^(th) element asthe possible value of the I component of the i^(th) element when thefirst Euclidean distance is greater than the first threshold, whereinthere is a plurality of constellation points in the constellation, andwherein each constellation point represents a possible candidate valueof the i^(th) element.
 10. The receiver according to claim 9, whereinthe processor is further configured to: obtain a second Euclideandistance between a Q component of the i^(th) element and a Q componentof the decision value of the i^(th) element through computation afterdetermining the I component of the decision value of the i^(th) elementas the possible value of the I component of the i^(th) element orsetting the I component value of the one or two constellation pointsclosest to the I component of the i^(th) element as the possible valueof the I component of the i^(th) element; determine the Q component ofthe decision value of the i^(th) element as a possible value of the Qcomponent of the i^(th) element when the second Euclidean distance isless than or equal to a second threshold; and set, according to theconstellation, a Q component value of one or two constellation pointsclosest to the Q component of the i^(th) element as the possible valueof the Q component of the i^(th) element when the second Euclideandistance is greater than the second threshold.
 11. The receiveraccording to claim 8, wherein the processor is further configured to seti to an integer from 1 to N sequentially, and separately perform thefollowing on an i^(th) element: make a hard decision on an I componentand a Q component of the i^(th) element to obtain a decision value ofthe I component of the i^(th) element and a decision value of the Qcomponent of the i^(th) element, wherein the i^(th) element is anelement in the N elements; obtain a first Euclidean distance between theI component of the i^(th) element and the decision value of the Icomponent of the i^(th) element through computation; determine thedecision value of the I component of the i^(th) element as a possiblevalue of the I component of the i^(th) element when the first Euclideandistance is less than or equal to a first threshold; and set, accordingto a constellation corresponding to the i^(th) element, an I componentvalue of one or two constellation points closest to the I component ofthe i^(th) element as the possible value of the I component of thei^(th) element when the first Euclidean distance is greater than thefirst threshold, wherein there is a plurality of constellation points inthe constellation, and wherein each constellation point represents apossible candidate value of the i^(th) element.
 12. The receiveraccording to claim 11, wherein the processor is further configured to:obtain a second Euclidean distance between the Q component of the i^(th)element and the decision value of the Q component of the i^(th) elementthrough computation after determining the decision value of the Icomponent of the i^(th) element as the possible value of the I componentof the i^(th) element or setting the I component value of the one or twoconstellation points closest to the I component of the i^(th) element asthe possible value of the I component of the i^(th) element; determinethe decision value of the Q component of the i^(th) element as apossible value of the Q component of the i^(th) element when the secondEuclidean distance is less than a second threshold; and set, accordingto the constellation, a Q component value of one or two constellationpoints closest to the Q component of the i^(th) element as the possiblevalue of the Q component of the i^(th) element when the second Euclideandistance is greater than the second threshold.
 13. The receiveraccording to claim 11, wherein the processor is further configured to:obtain a second Euclidean distance between the Q component of the i^(th)element and the decision value of the Q component of the i^(th) elementthrough computation after determining the decision value of the Icomponent of the i^(th) element as the possible value of the I componentof the i^(th) element or setting the I component value of the one or twoconstellation points closest to the I component of the i^(th) element asthe possible value of the I component of the i^(th) element; determinethe decision value of the Q component of the i^(th) element as apossible value of the Q component of the i^(th) element when the secondEuclidean distance is equal to a second threshold; and set, according tothe constellation, a Q component value of one or two constellationpoints closest to the Q component of the i^(th) element as the possiblevalue of the Q component of the i^(th) element when the second Euclideandistance is greater than the second threshold.
 14. The receiveraccording to claim 10, wherein the processor is further configured to:combine the possible value of the I component of the i^(th) element andthe possible value of the Q component of the i^(th) element to obtain amaximum possible candidate value of the i^(th) element; and obtain the Nmaximum possible candidate values.
 15. A receiving device, comprising: areceiver configured to receive an element sequence; a memory coupled tothe receiver and configured to store instructions; and a processorcoupled to the receiver and the memory, wherein the instructions causethe processor to be configured to: determine a maximum possiblecandidate value of each element in N elements of the received elementsequence to obtain N maximum possible candidate values, wherein N is apositive integer; determine state sequences corresponding to the Nmaximum possible candidate values as reserved sequences to obtain Ngroups of reserved sequences; perform likelihood computation on the Ngroups of reserved sequences; and set a reserved sequence that is in theN groups of reserved sequences and is most consistent with the elementsequence as a detected sent sequence.
 16. The device according to claim15, wherein the instructions further cause the processor to beconfigured to set i to an integer from 1 to N sequentially, andseparately perform the following on an i^(th) element: make a harddecision on the i^(th) element to obtain a decision value of the i^(th)element, wherein the i^(th) element is an element in the N elements;obtain a first Euclidean distance between an I component of the i^(th)element and an I component of the decision value of the i^(th) elementthrough computation according to the i^(th) element and the decisionvalue of the i^(th) element; determine the I component of the decisionvalue of the i^(th) element as a possible value of the I component ofthe i^(th) element when the first Euclidean distance is less than orequal to a first threshold; and set, according to a constellationcorresponding to the i^(th) element, an I component value of one or twoconstellation points closest to the I component of the i^(th) element asthe possible value of the I component of the i^(th) element when thefirst Euclidean distance is greater than the first threshold, whereinthere is a plurality of constellation points in the constellation, andwherein each constellation point represents a possible candidate valueof the i^(th) element.
 17. The device according to claim 16, wherein theinstructions further cause the processor to be configured to: obtain asecond Euclidean distance between a Q component of the i^(th) elementand a Q component of the decision value of the i^(th) element throughcomputation after determining the I component of the decision value ofthe i^(th) element as the possible value of the I component of thei^(th) element or setting the I component value of the one or twoconstellation points closest to the I component of the i^(th) element asthe possible value of the I component of the i^(th) element; determinethe Q component of the decision value of the i^(th) element as apossible value of the Q component of the i^(th) element when the secondEuclidean distance is less than or equal to a second threshold; and set,according to the constellation, a Q component value of one or twoconstellation points closest to the Q component of the i^(th) element asthe possible value of the Q component of the i^(th) element when thesecond Euclidean distance is greater than the second threshold.
 18. Thedevice according to claim 15, wherein the instructions further cause theprocessor to be configured to set i to an integer from 1 to Nsequentially, and separately perform the following on an i^(th) element:make a hard decision on an I component and a Q component of the i^(th)element to obtain a decision value of the I component of the i^(th)element and a decision value of the Q component of the i^(th) element,wherein the i^(th) element is an element in the N elements; obtain afirst Euclidean distance between the I component of the i^(th) elementand the decision value of the I component of the i^(th) element throughcomputation; determine the decision value of the I component of thei^(th) element as a possible value of the I component of the i^(th)element when the first Euclidean distance is less than or equal to afirst threshold; and set, according to a constellation corresponding tothe i^(th) element, an I component value of one or two constellationpoints closest to the I component of the i^(th) element as the possiblevalue of the I component of the i^(th) element when the first Euclideandistance is greater than the first threshold, wherein there is aplurality of constellation points in the constellation, and wherein eachconstellation point represents a possible candidate value of the i^(th)element.
 19. The device according to claim 18, wherein the instructionsfurther cause the processor to be configured to: obtain a secondEuclidean distance between the Q component of the i^(th) element and thedecision value of the Q component of the i^(th) element throughcomputation after determining the decision value of the I component ofthe i^(th) element as the possible value of the I component of thei^(th) element or setting the I component value of the one or twoconstellation points closest to the I component of the i^(th) element asthe possible value of the I component of the i^(th) element; determinethe decision value of the Q component of the i^(th) element as apossible value of the Q component of the i^(th) element when the secondEuclidean distance is less than a second threshold; and set, accordingto the constellation, a Q component value of one or two constellationpoints closest to the Q component of the i^(th) element as the possiblevalue of the Q component of the i^(th) element when the second Euclideandistance is greater than the second threshold.
 20. The device accordingto claim 18, wherein the instructions further cause the processor to beconfigured to: obtain a second Euclidean distance between the Qcomponent of the i^(th) element and the decision value of the Qcomponent of the i^(th) element through computation after determiningthe decision value of the I component of the i^(th) element as thepossible value of the I component of the i^(th) element or setting the Icomponent value of the one or two constellation points closest to the Icomponent of the i^(th) element as the possible value of the I componentof the i^(th) element; determine the decision value of the Q componentof the i^(th) element as a possible value of the Q component of thei^(th) element when the second Euclidean distance is equal to a secondthreshold; and set, according to the constellation, a Q component valueof one or two constellation points closest to the Q component of thei^(th) element as the possible value of the Q component of the i^(th)element when the second Euclidean distance is greater than the secondthreshold.